TY - JOUR A1 - Podshivalov, L. A1 - Wirth, Cynthia A1 - Zocca, Andrea A1 - Günster, Jens A1 - Bar-Yoseph, P. A1 - Fischer, A. T1 - Design, analysis and additive manufacturing of porous structures for biocompatible micro-scale scaffolds N2 - Advancements in the fields of biocompatible materials, manufacturing processes, computational methods and medicine have led to the emergence of a new field: micro-scale scaffolds for bone replacement and regeneration. Yet most such scaffolds produced today are characterized by very basic geometry, and their microstructure differs greatly from that of the actual tissue they are intended to replace. In this paper, we propose a novel approach for generating micro-scale scaffolds based on processing actual micro-CT images and then reconstructing a highly accurate geometrical model. This model is manufactured by means of a state-of-the-art 3D additive manufacturing process from biocompatible materials. At the micro-scale level, these scaffolds are very similar to the original tissue, thus interfacing better with the surrounding tissue and facilitating more efficient rehabilitation for the patient. Moreover, the approach facilitates the design and manufacture of patient-specific scaffolds which can copy patients’ exact structural and mechanical characteristics, taking into account their physical condition and medical history. By means of multi-resolution volumetric modeling methods, scaffold porosity can also be adapted according to specific mechanical requirements. The process of designing and manufacturing micro-scale scaffolds involves five major stages: (a) building a volumetric multi-resolution model from micro-CT images; (b) generation of surface geometric model in STL format; (c) additive manufacturing of the scaffold; (d) scaffold shape verification relative to the geometric design; and (e) verification of mechanical properties through finite element analysis. In this research, all the proposed stages of the approach were tested. The input included micro-CT scans of porous ceramic structure, which is quite similar to commercial porous scaffolds. The results show that the proposed method is feasible for design and manufacture of micro-scale scaffolds. KW - Micro-scale bone scaffolds KW - Additive manufacturing KW - Multiscale FEA KW - Ceramics KW - Multiresolution modeling PY - 2013 U6 - https://doi.org/10.1016/j.procir.2013.01.049 SN - 2212-8271 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 5 SP - 247 EP - 252 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-28003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Bernardo, E. A1 - Müller, Ralf A1 - Günster, Jens A1 - Colombo, P. T1 - LAS glass-ceramic scaffolds by three-dimensional printing N2 - Highly porous (>60% open porosity) glass–ceramic scaffolds with remarkable mechanical properties (compression strength of ~15 MPa) were produced by indirect 3D printing. Precursor glass powders were printed into 3D ordered structures and then heat treated to sinter and develop crystalline phases. The final glass–ceramic contained a β-spodumene solid solution together with a secondary phase of lithium disilicate. The precision of the printed geometry and the density of the struts in the scaffold depended on several processing parameters (e.g. powder size and flowability, layer thickness) and were improved by increasing the binder saturation and drying time. Two types of powders with different particle size distribution (PSD) and flowability were used. Powders with a larger PSD, could be processed within a wider range of printing parameters due to their good flowability; however, the printing precision and the struts density were lower compared to the scaffolds printed using the powder in a smaller average PSD. KW - Glass ceramics KW - Porosity KW - Shaping KW - Strength KW - Additive manufacturing PY - 2013 U6 - https://doi.org/10.1016/j.jeurceramsoc.2012.12.012 SN - 0955-2219 SN - 1873-619X N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 33 IS - 9 SP - 1525 EP - 1533 PB - Elsevier CY - Oxford AN - OPUS4-28284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Steinborn, Gabriele A1 - Tzschichholz, Grit A1 - Günster, Jens A1 - Keller, M.H. A1 - Manara, J. T1 - Porous TiO2-Y2O3 ceramics with specific infrared-optical properties N2 - The infrared-optical properties and particularly the emissivity of sintered ceramics depend on the material's bulk properties and structural properties such as porosity, pore size distribution and pore diameter. The infrared-optical properties can be varied across a wide range by specifically selecting the material's bulk and structural properties. A major concern of the present study is the development of a ceramic coating material with a total emissivity below 0.2 at a temperature of 800 °C. For this purpose, various samples of a TiO2-Y2O3 (TY) ceramic composite were produced with different properties. On variation in the Y2O3 content from 5 to 60 wt%, the porosity of the ceramic composites varies from 3 % to 47 % with the mean pore diameter lying in a range from 0.3 µm to 1.7 µm. The addition of graphitic pore builders increases the porosity up to 60 % and the mean pore diameter to a maximum of 15 µm. By optimizing the total porosity and the pore size of the TY ceramics, a total emissivity as low as 0.17 at 800 °C could be achieved. KW - Oxide ceramic KW - Porosity KW - Mean pore diameter KW - Infrared optical properties KW - Emissivity PY - 2011 U6 - https://doi.org/10.4416/JCST2011-00011 SN - 2190-9385 VL - 2 IS - 3 SP - 183 EP - 190 PB - Göller CY - Baden-Baden AN - OPUS4-24551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Wirth, Cynthia A1 - Mühler, Th. A1 - Heinrich, J. G. T1 - Direct Laser Sintering for the Manufacture of Ceramics: Status and Perspective T2 - XI Encontro da SBPMat CY - Florianópolis, Brazil DA - 2012-09-23 PY - 2012 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. AN - OPUS4-27840 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Wirth, Cynthia A1 - Mühler, Th. A1 - Heinrich, J. G. T1 - Additive Manufacture of Ceramics: Status and Perspective T2 - BIT's 1st Annual World Congress of Advanced Materials 2012 CY - Beijing, China DA - 2012-06-06 PY - 2012 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. AN - OPUS4-27841 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dombrowski, Felix A1 - Garcia Caso, P.W. A1 - Laschke, M.W. A1 - Klein, M. A1 - Günster, Jens A1 - Berger, Georg T1 - 3-D printed bioactive bone replacement scaffolds of alkaline substituted ortho-phosphates containing meta- and di-phosphates KW - Calcium alkaline phosphates KW - 3-D printing KW - Porosity KW - Compressive strength PY - 2013 U6 - https://doi.org/10.4028/www.scientific.net/KEM.529-530.138 SN - 1013-9826 VL - 529-530 SP - 138 EP - 142 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-26972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günster, Jens T1 - Vakuum im Pulverbett ersetzt Stützstrukturen KW - Additive Manufacturing KW - Ceramic KW - Selective laser sintering PY - 2013 SN - 1662-3096 SN - 0040-1498 SN - 0040-148X SN - 1023-0823 VL - 10 SP - 64 EP - 65 PB - Binkert Medien CY - Laufenburg AN - OPUS4-29936 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Dombrowski, Felix A1 - Garcia Caso, P.W. A1 - Laschke, M.W. A1 - Klein, M. A1 - Berger, Georg T1 - 3-D printed bioactive bone replacement scaffolds of alkali substituted orthophosphates containing meta- and diphosphates T2 - 37th International Conference and Exposition on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 2013-01-27 PY - 2013 AN - OPUS4-29884 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günster, Jens A1 - Mühler, Th. A1 - Heinrich, J. G. A1 - Wirth, Cynthia T1 - Powder based additive manufacturing of ceramic parts T2 - ICCPS-12 CY - Portland, OR, USA DA - 2013-08-04 PY - 2013 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. AN - OPUS4-29885 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mühler, T. A1 - Heinrich, J. A1 - Wirth, Cynthia A1 - Günster, Jens T1 - Slurry-based additive manufacturing of ceramics N2 - Most additive manufacturing (AM) techniques have in common that material is spread out as thin layers of a dried powder/granulate by a roller or a shaker system. These layers are mostly characterized by a low packing rate. On the other hand, appreciable densities can be reached by the use of ceramic slurries. In this context, the layer-wise slurry deposition (LSD) has been developed. Specific features of the LSD process are reflected on the basis of already existing additive manufacturing technologies. The microstructure of laser-sintered bodies will be discussed, and strategies for an improved microstructure during sintering will be introduced. KW - Additive manufacturing KW - Ceramic KW - Selective laser sintering PY - 2015 U6 - https://doi.org/10.1111/ijac.12113 SN - 1546-542X SN - 1744-7402 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 12 IS - 1 SP - 18 EP - 25 PB - American Ceramic Soc. CY - Westerville, Ohio AN - OPUS4-29937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -